Certain sensors, for example, optical turbidity—or nitrate probes for the water—and waste water field, are located over long periods of time in the medium to be measured. In such case, the measured signals and the required energy are transmitted via a connected cable. The exit of the cable from the sensor must, in such case, be sealed such that no medium can get into the sensor. This is accomplished, as a rule, by cable screw connections, whose sealing element is compressed radially around the cable jacket, such that there is plastic deformation upon the closing of the screw connection.
In order to fulfill requirements for electromagnetic compatibility (EMC) of the sensor, cable screw connections are used with special EMC connections. Involved, in such case, as a rule, are spring- or claw-shaped, metal elements, which, upon the screwing together, engage in the braided shield of the cable and hook there. Predominantly, the line to ground, and therewith, the EMC-drain, is routed via the outer conductor (also called the cable shield).
An opening of the cable screw connection for servicing is, as a rule, only possible with the application of considerable force and leads, most often, to destruction of the sealing element and to plastic deformation of the EMC connection.
The screw connection must, consequently, be completely replaced, in order to obtain a reliable sealing and a functional EMC connection. This is associated with considerable work and cost.